The overall objective is to sudy the manner in which microcirculatory structure and physiologic function are correlated. The program is a coordinated effort by six investigators, with specialized interests and methodologies, to systematically study the physiologic mechanisms associated with the control of microcirculatory pressure, blood flow and molecular exchange. In three projects microcirculatory alterations in the pathophysiologic states of hypertension and hypoxia are addressed. The approach to the work will include studies using both the whole organ and microvessel approach. The former approach includes lumped parameter measurements, while the latter includes direct measurement of microvascular variables. Every effort will be made to focus and correlate the information derived from the two different approaches to arrive at an overall understanding of the phenomena under study. Each investigator will apply his particular and special expertise toward testing specific hypotheses while the interaction between all investigators should provide a stimulating environment for the solution to problems and the generation of both new ideas and new directions for research. This application has components of study which are related to neural, hormonal, metabolic, myogenic and physical microvascular mechanisms. It is believed that a concerted research effort by a group of interacting individuals should yield important new insights into the physiology and pathophysiology of the microcirculation.